docs: def predict_effect(self, order, **kwargs):
          """Predict the effect of a goal.
  
          :arg order:  an order vector compatible with self.Mfeats
          :rtype:  same as order (if list, tuple, or pandas.Series, else tuple)
          """
          y = self.imodel.fmodel.predict_y(np.array(self._pre_x(order)), **kwargs)
          return self._post_y(y, order)